The set of points are .
It is a plane parallel to plane and units below it.
All points are in the form .
![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=1bb0c64c65ab3f81b10e2df4d3a066b3.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=730f9eecf7314d0487c180495151183f.png\")
plane and ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=d9285d5a293c4e12028128b0fb74ba46.png\")
units below it. ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=8055213d5d0ce27943f4887f72642202.png\")
. ![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")
.